Neither the writer nor the Webmaster nor Allpar take responsibility for any actions you may take or any consequences of applying the information, advice, and opinion in this article.
by "Blue" Mike Peterson, Schofield, WI
Front wheel drive is the wave of the future. It is indeed a “real” race car doing real racing. However, very little common knowledge info exists for front drives. My hopes are to share some of my experiences to save folks in our Mopar family some time and effort, at least give a baseline from where to start.
Before all, the best advice we can all get is, KEEP RECORDS!! Notes on every facet of your car, the race night, and your race performance. I have 100 pages of what didn't work, 4-5 pages no one else sees because it did work.
After every race or practice, take and record tire pressures. These stats tell you on the spot how much work each corner of your car is sharing. Your goal is to adjust to get all four sides to share in the work. When you find the right front overworked, hot and subsequently skyrocketing pressure, and the other three just along for the ride, work to even the load.
Tire temps tell you how each tire is working. A tire pyrometer, costing $65 and up, is an excellent investment. Temp readings on the outside, the center, and the inside (do it off to the side so brake heat doesn't confuse the readings) will tell you how well your initial tire pressures are working. For example, if the center is way hot vs the outsides, too much pressure, if the center is cooler, not enough. If the outside of the tire is hot and the rest cooler, the tire is not sitting properly to the ground.
Weight plays a key role. First rule of thumb is; lose as much of it you can. Lose every bracket, hinge, guard, even scrape the undercoating off. What has to stay according to rules can be trimmed and lightened, just make up for safety in your cage. If it doesn't sound worth the effort, put all this stuff in a bucket and weigh it at the end of your "diet session," you'll be surprised!
Bad places for unnecessary weight are hanging in front of the front wheels, behind the rear, and weight higher than a driver's waste level. Because it's hanging out it becomes unpredictable and multiplies with how far it is away from your tires.
If you have a weight rule, you can now place necessary weight where it benefits handling, low and left. On my Daytona, I cut out the spare wheel well, tin it flat, cut out behind the skirts, and with a little work, completely remove the inner wells on the rear tires (takes some time and break each pinch weld and the bulk comes right out leaving the bracing), then tape and use light weight materials to shield debris from coming in.) I do leave the shield under the right front keeping junk from getting up on the timing belt and pulleys, it's amazing what one little rock can do!!
Some rules prohibit adding ballast, but rules don't say, for example; you can't build your seat mounts with heavy HEAVY duty plating (low and left). Be sure your EEK has the aluminum bumpers found on 85 and up models, big weight break there!!!
Springs are a great tuning device. I found one turn cut off is good for 1 1/2 height, and INCREASES the spring rate (making it stiffer!) If rules say you can't cut your springs, sandblasting them and evenly heating them lowers the car just as well.
No one says you have to use springs out of a Mopar, and in my experience they don't even have to be the same diameter. Just clamp them to the spring bucket so they don't rotate or bind. Find springs from V-6 cars, and bigger models.
Offset wheels improve cornering. Chevy 5 bolt front wheel drive cars are the same bolt pattern (100mm), and the old 70-75 dodge dart wheels will fit with a little work. A lot of foreign stuff matches the 4 bolt pattern (also 100mm, just on 4 vs 5). Make a "jig" representing your pattern to quick measure all those wheels stacked up at the yard. I use Chevy Baretta 14"s on the right, which are offset bringing the tire away from the car, and OEM Mopars (shallower) on the left which positions the tires IN, more under the car.
The more the driver sits OVER the left wheels, the better. Offsetting the rights out makes the car behave as if it's a wider stance. Also, a tire size bigger on the right creates a "banking effect" helping you around those corners.
Make your car consistent. An older high mile chassis is loose, and most rubber mounts are junk. To stiffen things up:
On the front suspension and steering, spend some time getting it straight and check it often. A little nudge from another car can knock things way out. You don't need to run to an alignment shop either. Measure for toe by running a tape measure from a picked spot on the front of one the tire across to a like spot on the other tire. (draw a straight line around the circumference of the tire, or use a "toe plate", simply two boards half the height of your tires, and extending a little longer past the front and rear of your tires).
Then measure it across the back. Adjust the tie rod so they are the same. (Look down at your feet, each foot is a tire. If you are "duck footed", your toes point out in front although your heels are together thus "toe out".) Straight even is zero toe, or as I found, front wheel drives like it toed a bit out (fronts pointing outward up to an inch) as under power they suck the fronts in. Double check by running a string across the sidewall of the back tires, across the sidewall of the front tires. The string should just touch the front and back of the sidewalls, telling you the tires point straight and true in relation to the back tires.
Add camber. Camber is the relationship of the top of the tire pointing in or out as to the bottom. Imagine the car going around the corner (where most races are won and lost) You want that tire to be sitting on the pavement (or dirt) as flat as possible so, on the right side your tire should stand with the top tilted in (bottom sitting flatter in the corner) and the left tire should be with the top pointing out (the bottom in, and again, sitting flat around the corner.) Grind out the mounting holes in your strut towers, not too much to weaken the mounting spot, and grind out the bolts holes at the bottom of the strut oblong so you can add this camber. I suggest on the bottom holes to add shims inside the mounting holes like ground washers, bolts, what have you, to make up for the excess play so they don't shift on impact. TIGHTEN everything well, mark it, and always recheck your toe when done adjusting. Speaking of the strut towers, tie them into your cage or run a brace across side to side, once you bend the towers out of relation to themselves, it's hard to get things straight.
Incidentally, the strut "hats" which attaches the shock to the tower, has to move free and even, without play. For $15-20 a piece, buy 'em, and it's one of those things that can go from racecar to racecar. For final evaluation, tape measure from the center of the rear tire to the center of the front tire. Mark a spot in the center of the axles, have a helper hold the tape using some devise (like a T square) to bring the tape measure out far enough that it's straight, not bent in to touch the marked center. Side to side, they should be the same distance, if not, plan on using some chains and trees to pull one side back to be the same as the other.
On the track I personally prefer non powered steering as first reaction is always to over steer. There are manual racks out there, but disconnecting the pump (be sure to install the high and low pressure hoses together or you'll lose lubrication) does just fine for me. If you get a little scared when you wrench the wheel while sitting, fearing it may be too hard to steer, relax, at race speed, I doubt you'll even notice. You gain a couple horses not spinning the pump too.
These are some basics. Be willing to change your set up for YOU!! Other drivers surely mean well, but offer what works for them, and generally you're wrong and they're right. This gets confusing until you realize YOU are driving YOUR car, make it work for you. Just keep real good notes so you can revert back if an adjustment doesn't turn out the way you hoped.
IMPORTANT! There are more articles in this series. Click here for the next one. Click here for the previous one.
All Mopar Car and Truck News